Technical Field
This disclosure relates to a cooling device to cool a recording medium and an image forming apparatus incorporating the cooling device.
Related Art
Image forming apparatuses are known to include a cooling device to cool a heated recording medium with a cooling unit using, for example, a heat pipe or a heat sink. Further, a cooling device is also known to have multiple cooling units disposed on both sides of a recording medium in order to cool both sides of the recording medium effectively. In this case, the multiple cooling units are located shifted to each other in a sheet conveying direction.
When multiple cooling units are employed in an image forming apparatus, the multiple cooling units have the same cooling method.
Depending on a cooling method, however, a cooling device needs a specified space to be installed. Therefore, it may be difficult to dispose multiple cooling units employing the same cooling method or multiple cooling units with the same cooling method may not be installed due to a space requirement.
More specifically, when a cooling device employs a heat pipe roller, the heat pipe roller includes a roller and a radiation fin, and the diameter of the radiation fin is greater than the diameter of the roller. Due to this configuration, in a case in which multiple heat pipe rollers are aligned, the radiation fin of one heat pipe roller of the multiple heat pipe rollers interferes movement of the radiation fin of another heat pipe roller disposed adjacent to the one heat pipe roller. Even when respective positions of the multiple heat pipe rollers are shifted to have wider space therebetween in order to prevent the multiple heat pipe rollers from interfering with each other, the cooling device increases in size in a sheet conveying direction. In addition, a gap between two adjacent heat pipe rollers increases, resulting in deterioration of the cooling performance to a recording medium to be conveyed.
By contrast, when a cooling device employs a heat sink, the heat sink includes a fin extending in a vertical direction that interferes with a sheet conveying direction in which a recording medium is conveyed. Accordingly, when a heat sink is provided above and below the recording medium in the sheet conveying direction, the cooling device is extended in a vertical direction, and therefore the size of the cooling device increases.
Further, the cooling units having the same cooling method include respective heat absorbing surfaces having the same shape. Therefore, the cooling units have a sheet entry direction of the recording medium toward the cooling device and a sheet discharging direction of the recording medium from the cooling device, which is the same direction as the sheet entry direction.
Accordingly, a guiding member is provided to guide the recording medium after passing the cooling device toward a sheet discharging unit that is disposed at a position different from a sheet ejecting direction.
In addition, the cooling device may need to provide a belt disposed facing the recording medium to hold and convey the recording medium, and further respective belt drive units for the cooling units disposed at the upstream side and the downstream side in the sheet conveying direction.
Accordingly, a large section in which the recording medium is not cooled is provided between a cooling unit disposed at the upstream side and another cooling unit disposed at the downstream side. As a result, the image forming apparatus increase in size, and therefore the cooling efficiency deteriorates.